Self-lowering screw jack



April 6 1926; I 1,579,788

I F. H. SCHWERIN SELF LOWERING SCREW JACK Filed June 5, 1925 4 Sheets-Sheet 1 INVENTQR ATTORNEY v F. H. SCHWERIN SELF LOWERING SCREW JACK Filed June 5, 1925 4 SheetsSheet 2 IN VEN T0 Br 5 anon/v y 4 Sheets-Sheet 5 F. H. SCHWERIN SELF LOWERING SCREW JACK Filed Jun 5, 1925 April 6 192 4 w hmi um ul m v 4,3 lili 4 nwavron 7Z4 zymzm BY Arronufl April 6 1926. 1,579,788

F. H. SCHWERIN SELF LOWERING SCREW JACK I Filed June 5, 1925 4 Sheets-Sheet 4' Patented A r. 6, 192

incE.-

TENT or FRANK H. SCHWERIN, OF BELLEVUEiBOROUGI-I, PENNSYLVATTIA, ASSIGNOR TO THE DUFF MANUFACTURING COMPANY, OF lITTSBUl'l-GH, PENNSYLVANIA, A -COR- PORATION OF PENNSYLVANIA.

SELF-LOWEEING SCREW JACK.

Application filed June 5,1925. Serial No. 35,055.

To (1.7% 10720112 it may concern:

Be it known that I, FRANK H. Serrwnmrr, a citizen of the United States, and a resident of the borough of Bellevue, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Self-Lowering Screw Jack, of which the following is a specification.

The invention relates to that hind of self-lowering high-speed screw-jack covered by the Hindman Patent 1,234,334 ofJuly 24. 1917, having automatic and manual brake mechanism by means of which both the speed and the extent of the lowering n'iay be perfectlycontrolled without jarring or injury to the jaclgits load, or its support, under maximum loads. The present invention employs the means of the said patent for effecting safe and comparatively quick lowering and stopping of a heavily loaded jack, the object being to embody the same in a very simple, strong, compact, reliable, durable and effective construction.

In the accon'ipanying drawings forming part thereof:

Fig. 1 is an elevation of the lack, with the projecting portion of the main operating shaft in cross-section; v

Fig. 2 is a view on a larger scale looking at right angles to Fig. 1, taken on a central vertical section, with interior portions partly in elevation and the upper part .of the jack and the outer portion of the main operating shaft broken away;

F ig. is a vertical section on a still larger scale, taken approximately on the line 3-3 of Fig. 2, with portions broken out;

F igi 4: is a perspective viewof a casing part; i Fig. 5 is an enlarged horizontal sect on taken on the line 55 of Fig. 1, showing the handbrake free; and I Fig. 6 is a sectional view taken on the line 66 of F ig. 5, oi'l'iitting the fixed part of the casing. showing the hand-brake set.

The jack has a board supporting base 1 and a hollow standard or shell 2 rising from the base, the shell being preferably screwed to the base at 3. A narrow annex 4i adjoins the base andstandard and iscast in one piece with the standard, so as to have integral inner aiic outer vertical walls 5 aria tries ice" po tion 0 t wan 6 Was ii Y7. ii ,ir a.

horizontal main operating shaft 8. The

outer portion of this shaft, which is broken away in the drawings, will be understood as being operated by a ratchet lever in the usual manner. The inner end of the shaft 8 carries a bevel pinion 9, which meshes with a bevel gear wheel 10 on the .lowerend of a vertical lifting screw 11 of steep or rundown pitclnthis screw being. planted rotatably upon the base on an interposed ball bearing 12. A ram or load member 13 having a small head 14. is slidably telescoped in the standard 2, and is raised out of the standard by the screw 11, which passes upwardly through a nut 15 in the lower end of the ram into the Jrams hollow interior.

The loaded ram is raised step by step by the operation of the usual ratchet lever, not shown, and the pitch of the screwand nut is such that it will. run down when permitted.

Two horizontal auxiliaryshafts or axles 16, 17 extend across the interior of the annex i, parallel with the main shaft 8 and in transverse vertical alinement therewith, the

shaft 16 being above the shaft 8 and the shaft 17 above the shaft 16. The opposite ends of both these auxiliary shafts are supported solidly'in the integral walls or supports 5 and 6. A toothed wheel 18 is fixed to the main operating shaft 8 behind the bevel pinion 9 and -meshes with a spur pinion 19, which is rotatable on the shaft 16. The pinion 19 has a toothed wheel 20 fixed therewith, and said wheel meshes with a pinion 21 keyed to the rotary shaft 17. 3

Also keyed to this shaft there is a ratchet wheel 22. A pawl casing 23 is mounted rotatably on the shaft 17, and carries springratchet wheel, the pawl and ratchet form- 111g an overrunning clutch, which drives in one direction, namely the lowering direction, and runs free in the opposite or lift-- ing direction. The pawl case 23 is formed pressed pawls 24 to engage the teeth of the i the circumference of the disk and forming pivots for the limbs 31 of centrifugal weight segments 32 which project from the outer face of the disk. These pivots are transverse to the axis of rotation 16. The arcuate surfaces of these segments revolve within an encircling smooth friction wall 38 in "the annex casing and are normally drawn away from this wall by springs 3i connecting the segments.

An arcuate brake shoe 35 is disposed adjacent the circular periphery of the disk 27, and is operated by a screw 36, which is threaded through an internally screwthreaded boss 37 on one side of. the annex casing. This screw has a swivel connection 38 with the brake shoe and is operated hy an external handle 35) so as to operate the brake shoe 35 positively, to apply the same to the disc or to release it therefrom. The brake shoe S5 is kept :tron'i turning on the swivel by reason of its side being immediately adjacent the edge of the inwardly pro jecting flange it of a cap 41, as is shown in -Fig. 5.

This cap it is set into a circular opening J2 in the outer wall 6 of the annex casing, and its central, boss 43 forms a support for the shaft 16 of the centrifugal brake. The cap is secured in place by bolts i -it, and this separate part contains the set of finished surfaces necessary for the accurate operation of the centrifugal brake. These surfaces include the outercyliinlrical surface of the flange l0, which fits into the circular openins e2, which is concentric with the axis OI the shaft 16, and the inner cylindrical surface 33 with which the centrifugal segments cooperate when they are urged outward by centrifugal force; and the cap likewise has the central supporting boss 46 for the shaft 16. The .tinished portions of the cap are concentric and can be accurately andcheaply formed by placing this small casing part upona suitable rotary machine. The mechanism within the annex is introduced through the opening 4-2 occupied by this ca-p,'through another opening in the upper side wall of the-annex chamber at the side opposite the handle 39, this opening being closed by a bolted cover plate 4-7, and/or through the bottom of the shell 2 before the base 1 has been put in place.

The positive lateral pressure of the brakeshoe 35 against the disk 27 might, if the screw were set hard cnougln injuriously l: 'nd the shaft 32, or cause some injury. To avoid this, the 'ap flange 40 is provided. on one portion, at the side-opposite from the brakeshoe, with an extension 48, the curved surfaces of which are finished in continuity with the body of the flange. This extension lies opposite and very close to the periphery of the disk 2?, there being a slight normal clearance s 9, exaggerated in Fig. permitting the disk to run free when the manual brake is released. \Vhen the brake is set ha d, the shaft and disk will be displaced to a slight extent, exaggerated in Fig. ti, so that the disk bears against the extension or lixed guard l8. Thereby injury is prevented, and the brake lo mg is made even more secure since the disk is clamped betr-ceen the sta tionary and movable s gments 35 and ell). The extremely small displacement of the disk which is permitted may bend the shalt, but only to a trifling degree, which can cause no injury and which is well within the limit of elasticity.

All the auxiliary gearing necessary to operate the centrifugal brake consists of a few spur gears and the overrunning clutch, mounted on the two horizontal. auxiliary shafts it; and 1'? above and parallel with the main operat shaft 8, and the ratio of the simple spcec multiplying gearing from the bevel gear 10 to the end of the short spur gea. train is such as to produce the requisite centrifugal eltect' at the brake. The combination and arrangement of parts with the manual and automatic brakes cmisolidated on the axis of the shaft 16 and the OVGllllll' ning clutch on the axis of the shaft 17 give the greatest sensitivencss and reliability in the braking means, permit very slight, if any, sink-hack after each stroke of the lifting lever as the pawls oft-he over-running clutch take hold, enable the ovorrunning clutch to be comparatively small and light, and contribute in an important manner to the coinpactness and moderate weight of the jack for the heavy duty which it has to perform. In lowering, the heavy load is held to a constantsafe rate of descentby the centrifugal brake continually checking the speed; and the load is stopped promptly and accurately at any point by positive application of the hand brake without danger of injury.

hat I claim as new is:

1. A screw jack having a has and a load member and a run-down lifting screw for raising the load, a cas ng and acentrifugal brake mechanism therein geared to the screw, the casing having a circular opening concentric with the axis of the centrifugal brake mechanism, and a cap for said opening, said cap having a central support for the rotary part of the centrifugal brake and being provided with external and internal surfaces, respectively lifting the casingand to cooperate frictionally with said rotary part of the centrifugal brake.

2. it screw jack having a base and a load member and a run-down lifting screw for raising the load, a casing and'a centrifugal brake mechanism therein geared to the screw, said mechanism having .a rotary disc, pivoted centrifu al segments projecting from a face of said disc, the pivots of said segments being transverse to the axis of' rotation of the disc, a stationary wall in the casing encircling sald segments, a brake shoe cooperative with the periphery of said disc,

ating shaft in the casing geared to said.

screw, two auxiliary shafts in the casing parallel with the main operating shaft, gears on the several shafts for driving from the main shaft to the first auxiliary shaft, thence to the second auxiliary shaft, and thence back to the axis of the first auxiliary shaft, an overrunning clutch on said second auxiliary shaft, a brake disc on the axis of the first auxiliary shaft, a manually operated brake cooperative with said brake disc, and centrifugal brake elements carried by said disc tocooperate with a stationary surface.

4. A screw jack comprising a base, a hollow standard rising from the base, an annex adjoining the base and standard and having outer and inner walls cast in one piece with the standard, a ram slidable in the standard, and a rundown screw for raising the ram, a main operating shaft journaled in the lower part of the outer wall of the annex and carrying a pinion for driving the screw, a toothed wheel on said main shaft, horizontal auxiliary shafts in the annex above themain operating shaft supported at their opposite ends in said inner and outer walls, a centrifugal brake and gearing mounted on said auxiliary shafts between said walls for driving said centrifugal brake from the toothed wheel on the main shaft. I

5. A screw jack having a base and a load member, a run-down lifting screw for raising the load, means for operating the screw for raising, and a holding and lowering mechanism, said mechanism having a brake disc,a positively-operated mechanical brake applicable to the periphery of the disc, and a fixed guard at the opposite side of said periphery against which said brake locks the disc.

.6. A screw jack having a base and a load member, a run-down lifting screw for raising the load, means for operating the screw for raising, and a holding and lowering mechanism, said mechanism having a brake disc, :1 brake-shoe opposite the periphery of said disc, an operating screw arranged to set the ln'ake-shoe positively against the disc,

a casing, and a fixed arcuate guard on the interior of said casing immediately adjacent said periphery at the side opposite from the brake-shoe. I

7. A screw jack having a base and a load member, a run-down lifting screw for raising the load, and operating means for rotating the screw to lift the load; a casing, and

brake mechanism therein having a one-way A screw jack having a base and a load" acting connectionwith the screw, said brake mechanism having a brake disc, centrifugal friction segments carried by said disc, said casing having a circular opening concentric with the axis of said disc, a cap for said opening, said cap having a central support for-said disc and a circular flange fitting the opening in the casing and affording an encircling friction surface to cooperate with said centrifugal segments, a portion of said flange lying closely adjacent the periphery of the brake disc so as to limit displacement, and a manually operated brake member cooperative with the periphery of the disc at the opposite side.

8. In a screw jack, a base, a hollow standard thereon, a load member slidable in the standard, and a rundown lifting screw for raising the load, an annex casing with integ'al inner and outer walls cast in one piece with the hollow standard, a horizontal operating shaft geared to the screw, other horizontal shafts extending across the in tcrior of said annex casing above the operating shaft and supported at their opposite ends in said inner and outer walls, a rotary brake member on one of thesev shafts, a cooperative brake member, gearing on the shafts for driving said rotary brake member from the screw in lowering, the outer wall of the annex casing having a'circular opening, and a cap having a circular centering flange fitting said opening and a concent *ic support for the outer end'of the brake shaft. I

9. In a screw jack, a base, a hollow standard thereon, a load member slidable in the standard, and a run-down liftingscrew for raising the load, an annex casing with lIl-' tegral inner and outer walls cast in one piece with the hollow standard, a horizontal operating shaft geared to the screw, other horizontal shafts extending. across the interior of said annex casing above the opermatic brake .member from the screw in lowthe outer wall of the annex casing having a circular opening, and a cap having ering,

a circular centering flange formed on the outside to fit. said opening and on the inside to cooperate with said automatic brake member and having a central support for the outer end of the brake shaft.

10..In a screw jack, a base, arhollow standard thereon, a load member slidable in the standard, and a run-down lifting screw for raising the load, an annex casing with integral inner and'outer walls cast in one piece with the hollow standard, horizontal shafts extending. across the interior of said annex easing with their opposite ends sup ported in said inner and outer walls, a centrifugal brake n'iember on one of said shafts, gearing on the shafts for driving said brake member from the screw in lowering, said outer wall having a circular opening, and a circular cap centered at said opening and carrying means to cooperate with said brake member and a central support for the brake shaft.

11. In a screw-jack of the self-lowering type, having a base and a load member, a run-down screw for raising the load, and a horizontal main operating shaft geared to the screw, a casing having an outer wall and an inner support spaced therefrom, said outer wall containing an opening. a plurality of horizontal shafts parallel with said main. operating shaft extending across between i said outer wall and inner support, a contrifugal brali'e member on the axis of one of said parallel shafts adjacent said opening in the outer wall, gearing arranged on the axes of said shafts for driving said centrifugal brake member from the main operating shaft in lowering, and a cap applied to the opening in said outer wall and carrying a stationary braking surface to co-operate with said centrifugal brake member.

12. In a screw-jack of the self-lowering type, having a base and a load member, a run-down screw for raising the load, and a horizontal main operating shaft geared to the screw, a casing having an outer wall and an inner support spaced therefrom, said outer wall containing an openin a plurality of horizontal shafts parallel with said mam operating shaft ex tending across between said outer wall and inner support, a centrifugal brake member on the axis of one of said parallel shafts-adjacent said opening in the outer wall, gearing arranged on the axes of said shafts for driving said centrifugal brake member from the main operating shaft in lowering, and a. cap having a circular flange formed with concentric outer and inner surfaces, the outer of said surfaces being a centering surface fitting within said opening and the inner-surface being a stationary braking surface encircling said centrifugal brake member.

13. In a screw-jack 0f the self-lowering type, having a base and a load member, a run-down screw for raising the load, and .-i horizontal main operating shaft geared to the screw, a casing having an outer wall and an inner support spaced therefrom, said outer wall containing an opening, a plurality of horizontal shafts parallel with said main operating shaft extending across between said outer wall and inner support, a centrifugal brake member on the axis of one ofsaid aarallel shafts adjacent said open ing in t ieouter walhgearing arranged on the axes of said shafts for driving said ecutrifuga'l brake member from. "the main operiiiefinber and ating shaft in lowering, and a cap formed with a central support for the outer end of the centrifugal brake shaft and with concentric outer and inner surfaces, the outer of said surfaces being a centering surface litting a corresponding surface of said outer wall and the inner surface being a station ary braking surface encircling said cen trifugal brake member.

ll. In a screw-jack of the self-lowering type, having a base and a load member, a run-down screw for raising the load, and means for act atiug the screw, a casing .the outer wall of which is provided with a circular opening, a centrifugal brake member in the casing with gearing for driving said centrifugal brake member from the screw in lowering, and a cap having a circular flange formed with concentric outer and inner surfaces, the outer of said surfaces being a centering surface lit-ting within said opening and the inner surface being a stationary braking surface encircling said centrifugal bral-ze member.

if). [n a screw-jack of the self-lowering type, having a base and a load member, a run-down screw for raising the load, and means for actuating the screw, a casing the outer wall of which is provided with a circular opening, a centrifugal brake member in the casing with gearing for driving said centrifugal brake member from the screw in lowering, and a cap provided with an axial support for said centrifugal brake member and with concentric circularly formed surfaces, the outer of said surfaces being a centering surface fitting the corresponding surface of said outer wall and the inner surface being a stationary braking surface cooperative with said centrifugal brake member.

16. In a screw-jack of the self-lowering type, having a shell, an inner part, a rundown lifting screw threaded in said inner part, and means for actuating said screw, said shell being formed with an annex chamber with spaced outer and inner walls cast integral with the shell, the outer of said walls formed with a. circular opening, aplurality of pa 'allel horizontal shafts extending across between said walls, a. centrifugal brake member on the axis of one of said shafts, means having meshing gears on the axes of said shafts for driving said centrifugal brake member from the screw in lowering, and a circular cap applied'to said opening affording a central support to said centrifugal brake member and its shaft and formed with outer and inner circularly formed surfaces, the outer of said surfaces being a centering surface fitting the corresponding surface of said outer wall and the inner surface cooperating with said centrifugal brake member.

17. A screw jack having base and a load rut down screw for raising the load, a casing, a horizontal main operating shaft in the casing geared to said screw, tWo auxiliary shafts in the casing parallel with the main operating shaft, gears on the several shafts for driving from the main shaft to the first auxiliary shaft, thence to the second auxiliary shaft, and thence back to the axis of the first auxiliary shaft, an overrunning clutch on said second auxiliary shaft, a brake disc on the axis of the first auxiliary shaft adjacent the outer Wall a" manually operated brake of the casing,

with said brake disc, cencooperative trifugal brake elements carried by said brake disc, and a special cap on said outer Wall of the casingsupporting the outer end of said first auxiliary shaft and carrying at its inner side a stationary brake surface to cooperate with said centrifugal brake elements;

FRANK H. SCPHVERIN. 

